feat: 四归一/圈风/门风/单钓将识别器 + GameState状态跟踪

新增4个番型识别器:
- 四归一: 4张同牌跨面子使用(不在单个kezi/kong) — 纯结构检测
- 圈风: 当前风圈对应的风刻(31=东/32=南/33=西/34=北)
- 门风: 玩家座位风位对应的风刻(庄=东)
- 单钓将: 自摸时摸到的牌完成了将牌的单吊对子

GameState扩展:
- WindRound(当前风圈) + SeatWinds(玩家→风向) + IsSingleWait flag
- Deal()分配座位风位(庄家=东,按逆时针)
- StepTurn自摸时检测单钓将(摸牌←→对子匹配)

效果: 国标--check 6→0 (圈风/门风/单钓将/四归一全部消除)
所有玩法合规检查通过(南昌/血战仅base_fan=0标记警告)

RuleEngine/MahjongRoom.cs

@@ -239,7 +239,23 @@ public class MahjongRoom
             var result = _solver.CheckWin(fullHand,
                 wildcardCount: wildInHand, require258Pair: r258);
             if (result != null)
+            {
+                // 单钓将: drawn tile completed a pair from a singleton
+                if (State.LastDrawnTile.HasValue && result.PairTiles.Count == 2)
+                {
+                    int drawn = State.LastDrawnTile.Value;
+                    if (result.PairTiles.Contains(drawn))
+                    {
+                        int other = result.PairTiles[0] == drawn ? result.PairTiles[1] : result.PairTiles[0];
+                        // Before drawing the winning tile, hand had 1 of the other pair tile
+                        var handBefore = new List<int>(fullHand);
+                        handBefore.Remove(drawn);
+                        if (handBefore.Count(t => t == other) == 1)
+                            State.IsSingleWait = true;
+                    }
+                }
                 result.Fans = _solver.IdentifyFans(result, State);  // event-based fans
+            }
             State.HuPlayers.Add(player);
             State.AlivePlayers.Remove(player);
             State.AddEvent("win", player, null,
@@ -758,6 +774,15 @@ public class MahjongRoom
 
         State.AddEvent("deal_done", "", null, "发牌完成");
 
+        // 圈风/门风: assign seat winds based on player order relative to dealer
+        int[] winds = { 31, 32, 33, 34 }; // 东南西北
+        int dealerIdx = State.PlayerOrder.IndexOf(State.Dealer);
+        for (int i = 0; i < State.PlayerOrder.Count; i++)
+        {
+            int windIdx = (i - dealerIdx + 4) % 4;
+            State.SeatWinds[State.PlayerOrder[i]] = winds[windIdx];
+        }
+
         // Random wildcard (骰子翻牌定精): flip one tile from remaining deck to determine 精
         if (_rules.WildcardRules?.Type == "random" && State.Deck.Count > 0)
         {